1. Field of the Invention
The present invention relates to a semiconductor device manufacturing method and a semiconductor device manufacturing apparatus, and especially relates to a semiconductor device manufacturing method and a semiconductor device manufacturing apparatus which accurately control film thickness (film formation rate) in a batch-type film-forming apparatus, suppress manufacturing variation of semiconductor devices, and improve a manufacturing yield.
2. Description of the Related Art
As design rules of semiconductor devices become finer, more accurate control is demanded in manufacturing technologies of transistors and wirings. In manufacturing processes such as thermal oxidation, thermal diffusion, CVD (Chemical Vapor Deposition), and annealing which is one of its constituent technologies, a reduction of thermal budget is required in formation of thin films and ultra shallow junctions (USJs) of doped impurities. Therefore, in place of a batch type low-pressure CVD apparatus which is a furnace-type manufacturing apparatus long used for manufacturing semiconductor devices, a single-wafer-type rapid thermal processor (RTP) has come to be used. However, when forming a film of a small film formation rate to a relatively large film thickness of a dozen to several ten nm, because a single-wafer type manufacturing apparatus has a low manufacturing throughput, a manufacturing cost increases significantly. Therefore, a furnace-type manufacturing apparatus, which is a batch type, having a high productivity is used even at present.
As semiconductor devices become further minute, slight changes in the state of a manufacturing apparatus come to influence performances of the manufacturing process, making it difficult to realize a stable process just by controlling the manufacturing apparatus itself. For example, in the case of an oxide film-forming apparatus, even if temperature of wafers and temperature within the film-forming apparatus are controlled to be the same, depending on an apparatus condition of the film-forming apparatus, the thickness of an actually formed oxide film varies. In that case, sometimes used is an advanced process control (APC) which measures the oxide film thickness at a process monitor on the wafer, adjusts a processing time based on the measured film thickness to adjust to a target film thickness.
For example, a method described in Japanese Patent Application Laid-Open No. 2007-59945 is one of the APCs. In this priority document, in a manufacturing apparatus such as a furnace which performs manufacturing processes by thermal treatment, a low-pressure CVD apparatus, and an RTP, a process controller is installed. It is proposed that the oxide film thickness be calculated in the controller based on gas flow rate or temperature obtained from the manufacturing apparatus and that processes in the manufacturing apparatus be stopped when a desired oxide film thickness is reached.